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Tuesday, May 31, 2011

First milk (colostrum) for the enhancement of healing and recovery after an injury?

Among the supplements used for recovery is bovine colostrum. Colostrum is the breast milk produced in the first few days after the mother gives birth. This milk is higher in protein, immunoglobulins and insulin-like growth factors (IGFs) than the “mature” milk. Commercial colostrum supplements are produced from bovine (cow) milk. Chronic use (few weeks) of these supplements is suggested to improve performance and recovery rate in athletes. However, not all studies show a beneficial effect of bovine supplements on performance and recovery.

In the past, colostrum has also been used for wound healing in animals (Leitzel et al., 1985). Since colostrums is high in IGF-1 it could be speculated that supplementation might help in healing after an injury. Indeed, studies in animals show that IGF-1 stimulates muscle healing and may have a considerable effect on the treatment of muscle injuries (Menetrey et al., 2000). However, these results are based on animal studies and have examined the effect of a single factor on healing process. No doubt, that there are also additional growth factors involved in tendon, muscle and ligaments healing and this should be taken into account when evaluating the results of these studies. It seems that more research is needed on the effect of bovine colostrum supplementation on the healing process after a sport injury.


For more reading
Molloy et al. Sports Med 33(5):381-94, 2003

Monday, May 30, 2011

Salivary analysis: applications in football

Salivary collection and analysis is rapidly developing as a tool for the assessment of physiological biomarkers of sports training. The use of saliva for monitoring steroid, peptide, and immune markers in sport and exercise has made saliva sampling and analysis very attractive to sports scientist in the field. Saliva can provide a useful, non-invasive alternative to the collection of serum and plasma, because it can be collected rapidly, frequently and without stress. Furthermore, salivary collection requires less medical training and can be performed on the sports field. 


What measurements can we perform in saliva?
Hormones and immune markers concentration associated with overtraining can be determined with salivary analysis. Indeed, there are now kits available for the determination of testosterone and cortisol levels. To remind you, the testosterone/cortisol ratio is used as an indication of the anabolic/catabolic balance. This ratio decreases in relation to the intensity and duration of exercise, as well as during periods of intense training or repetitive competition, and can be reversed by regenerative techniques. Immune markers are detectable in saliva as well and help to determine the risk of respiratory infections.

Is salivary composition similar to the blood?
Total concentrations of most of these compounds are much lower in saliva when compared with serum or plasma. It seems, however, that they can provide a reliable reference for their respective blood concentrations.

Is saliva collection easy?
Yes, it is.  Before sampling, players must avoid food or drink intake as well as exercise.   About 10 min before sampling, players must wash their mouth with water. Players should avoid brushing their teeth.

For more reading
Papacosta and Nassis. Journal of Science and Medicine in Sport, April 6, Epub ahead of print

Sunday, May 29, 2011

CHAMPIONS LEAGUE FINAL STATISTICS

Below you can see some numbers from the 2011 final held in London. These are the official stats from UEFA http://www.uefa.com/uefachampionsleague/matches/season=2011/live/index.html?matchday=13&day=1&match=2003352

  • 12 attempts on target for Barcelona, 1 for Manchester United.
  • 63% ball possession for Barca.
  • The total number of passes that Barcelona made in the final was 777.
  • 357 passes for Manchester United.
  • Successful passes rate was 90% for Barcelona team. United's was 80%.
·         Barca’s midfielder Xavi completed 136 passes during the game. He misplaced only 12, giving him a completion rate of 91%.
  • Xavi covered 11,950 m the highest distance in the team followed by Inesta (10,640 m). Messi covered 9,130 m.
  • Giggs covered the greatest distance for Mann United (11,160m) followed by Rooney (10,500 m in total).

Wednesday, May 25, 2011

DIFFERENCES BETWEEN A WINNER AND A LOSER: DOES BRAIN PLAY A ROLE?

Classically the physiological limits to performance in football and in other sports may be cardiovascular and/or metabolic. However, this view does not explain the situation in a match when players stop exercising without significant legs’ fatigue and cardiovascular stress. It seems that something else beyond the muscles and the heart function is related to our decision stop exercising. Several studies over the last years provide evidence on the role of the brain and in particular of the central nervous system on exercise performance.

Data agree that exercise starts and ends in the brain. It starts with partial motor unit recruitment and stops with motor unit de-recruitment. According to this hypothesis, the central nervous system (CNS) integrates signals from various sources in the body (working muscles, arteries, peripheral organs) and limits the recruitment of motor units in an attempt to maintain homeostasis. Brain is trying to protect us from serious damage.

Therefore, exercise is stopped by a forced decision from the brain not to go far a certain point before “catastrophe” occurs. Brain is protecting us from serious damages. It seems that limitations set by the central nervous system may deteriorate performance.

 It remains clear that genetic abilities and high physical capacity lead to high performance but in a match the difference between a winner and a loser may be not so much on physical aspects but in how big is the safety margin set by the central nervous system. Perhaps elite performers do so well because they are able to push the limits set by the CNS closer to the danger zone which would explain their success when playing against players with similar physical and other abilities.

Tuesday, May 24, 2011

EFFECTIVENESS OF COMPRESSION GARMENTS AS A RECOVERY STRATEGY

Several teams and individual players use compression garments as a means of speeding up recovery after training and/or match. There are at least 4 papers in the literature investigating the effectiveness of wearing compression garments on recovery rate in football and team sports players (Gill et al., 2006, Duffield et al., 2008, Duffield et al., 2010, Jakeman et al., 2010). They all agree that players feel less muscle soreness when wearing garments during recovery following training. However, the majority of them (3 out of 4) agree that the effect of compression garments on performance the days after training/match was minimal or that there was no effect.

Moreover, wearing compression garments is as effective as contrast water therapy and low intensity exercise after the match in speeding up recovery.

Despite the lack of improvement in performance or recovery, there is evidence that wearing whole body compression garments might increase high-intensity intermittent exercise performance (Sear et al., 2010). This study, however, refers to wearing the whole body compression garments. More information is needed on the effect of lower-body or lower-legs compression garments which are more practical approaches in football.

Sunday, May 22, 2011

ANTIOXIDANT SUPPLEMENTATION MAY REDUCE TRAINING-INDUCED ADAPTATIONS: NOVEL FINDINGS

Reactive oxygen species (ROS) are produced at an increasing rate when metabolism is elevated such as during exercise training.  Athletes usually consume antioxidants in an effort to reduce ROS, reduce muscle damage and thus minimize fatigue. A recent study in the Medicine and Science in Sports & Exercise (Strobel et al., 2011) examined the effect of long-term antioxidant supplementation with vitamin E and α-lipoic acid on changes in markers of mitochondrial biogenesis in the skeletal muscle of rats. Their results showed that antioxidant supplementation suppresses skeletal muscle mitochondrial biogenesis.

If this is also true in humans, it means that antioxidant supplementation reduces the magnitude of adaptation and benefits gained by aerobic exercise training.

Wednesday, May 18, 2011

Acute dietary nitrate supplementation improves performance

A new study, conducted by researchers in the University of Exeter UK, was published few days ago on the effect of acute dietary nitrate supplementation on performance in a simulated cycling race (Lansley et al., 2011). Nine competitive male cyclists were assigned in a randomized, crossover design to consume 0.5 L of beetroot juice (containing 6.2 mmol of nitrate) or 0.5 L of nitrate-depleted beetroot juice 2.5 h before the completion of a 4- and a 16.1-km time trial. The results showed that acute dietary nitrate supplementation improved cycling time trials by 2.8% and this was a significant improvement compared with the control trial.

These results together with those from other studies suggest that dietary nitrate supplementation may improve endurance performance.

Fernando Torres and Functional Strength Training

There are at least two issues when designing strength training for elite players 1) transformation of strength gains achieved in the gym in the actual play in the field, 2) preparing exercises that are specific for the muscle action and the speed achieved in football. Classic weight training and exercises, like squats, may not be very effective in improving power in the field.

Modern approaches using mainly players' body weight have been developed. Benefits are: 1) specificity of movement and muscle action, 2) training can be performed anywhere.

Below you can view 2 links on functional strength training.

Fernardo Torres doing functional training

http://www.trxspain.es/index.php?option=com_flexicontent&view=items&cid=34&id=150&Itemid=60
http://www.youtube.com/watch?v=3MJUYCwy4-g&feature=fvwrel

Tuesday, May 17, 2011

VARIATIONS IN INJURY INCIDENCE OVER THE SEASON IN ELITE PLAYERS

In the UEFA injury study, injury incidence was followed for the first team squad of 23 top level teams (among others Arsenal FC, Mann Untd, Chelsea FC, Liverpool FC, FC Inter, AC Milan, Real Madrid, FC Barcelona, FC Porto, SL Benfica) from 2001 to 2008. Traumatic injuries and hamstring strains were more frequent during the competitive season, while overuse injuries were the most common in the preseason period.

The mean total injury incidence was 8/1000 hrs of exposure. The injury incidence was >6 times higher during matches than during training. The injury incidence, both in training and in matches, did not differ between seasons.

DISTRIBUTION OF INJURIES DURING A MATCH IN THE UEFA STUDY: Implications for training

Table 1 below shows the distribution of injuries during a match as reported in the UEFA injury study recently published by Ekstrand and colleagues (2011). The incidence of muscle injuries showed an increasing tendency towards the end of both halves. This could be attributed to muscle fatigue. Indeed, previous studies show that physical performance is lower towards the end of the second half and this increases the risk for muscle injuries. Another interesting finding from the literature is that hamstring strength declines towards the end of the match and this might be associated with elevated risk of hamstring injury. Injury risk may be greatest with muscle weakness during eccentric contractions.

Together these results suggest that 1) hamstring strength and in particular eccentric strength declines towards the end of a match, 2) training should include eccentric contractions for the hamstrings especially at the end of session.

Table 1. Distribution of injuries during a match: results from the UEFA injury study (adapted from Ekstrand et al., 2011).

No of Sprains
No of Strains
Total No of Injuries
1-15 min
10
25
50
16-30 min
21
35
90
31-45 min
38
55
140




46-60 min
20
40
80
61-75 min
30
60
145
76-90 min
25
40
120

Monday, May 16, 2011

Does stretching and/or increased flexibility reduce muscle injuries in football?

Studies show that elite football players suffer about 2 performance-limiting injury per year. Injuries imply days of training loss and reduction in training load in the following period; both result in a decline of physiological adaptations and performance.
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Although injury incidence has been researched adequately, little is known about the risk factors in football players. A lack of muscle flexibility has long been considered as an important risk factor for injury occurrence in football players. Hence, stretching exercises are regularly recommended as part of football training. The mechanism by which stretching exercises can reduce muscle injuries is not clear yet. It seems that increased visco-elastic properties of a muscle can decrease the strain in a muscle and thus protect from an injury.

In reviewing recent literature in football players several conclusion can be made which are summarized below:
·         Research conducted in football players suggests an association between stretching and/or increase flexibility and injury incidence reduction.
·         Regular acute pre-exercise stretching practices seem not to protect from muscle injuries during the match.
·         4-5 sets of 60-90 sec of static or ballistic stretching seem to be a good practice. Based on the present studies, no recommendation can be made on the optimal long-term program.
·         As mentioned above, there seems to be no difference between ballistic and static stretching in injury protection in football players at least when a single program is considered.
·         Regarding long term training, it seems that ballistic stretching offers better protection from all injuries compared with static stretching.
·         There is evidence that static stretching can reduce the incidence of musculotendinous and ligament sprain type injuries, but not overall injury rates.

Wednesday, May 11, 2011

INJURIES IN PROFESSIONAL FOOTBALL PLAYERS: THE UEFA STUDY

Players from 23 of the 50 best teams selected by UEFA served as the participants of the UEFA injury study the results of which were published yesterday.

Briefly, the aim of this study was to examine the injury characteristics in professional football players and to follow the variation of injury incidence during a match, during a season and over consecutive seasons. Hence, team medical staff recorded individual player exposure and time-loss injuries from for 7 consecutive years (2001 to 2008).  The main findings were:
  • Injury incidence rate was 8.0 injuries/1000 h.
  • Injury incidence was higher during matches than in training.
  • A player sustained on average 2.0 injuries per season, and a team with typically 25 players can thus expect about 50 injuries each season.
  • Thigh strain was the most common injury subtype (17% of all injuries).
  • Re-injuries constituted 12% of all injuries; they also resulted in longer absences than non re-injuries (24 vs 18 days).
  • Match time was associated with injuries. Indeed, incidence of match injuries increased over time in both the first and second halves.
  • In competitive season, traumatic injuries and hamstring strains were the most frequent.
  • In pre-season, overuse injuries were the most common.
  • Training and match injury incidences were stable over the period with no significant differences between seasons.

HIGH-INTENSITY TRAINING FOR FOOTBALL PLAYERS

High-intensity training is an important component of football training in modern, elite level football. Match analysis has revealed that the most successful teams perform more high-intensity activities than the less ones. Hence, football players need a high fitness level to cope with match demands. Studies on football players show that 8-12 weeks of aerobic high-intensity running training (>85% of maximal heart rate) improve maximal oxygen uptake by 5-10% and lower submaximal blood lactate concentration. Speed-endurance training improves football-specific endurance as indicated by 20-25% improvement in Yo-Yo test and the ability to perform repeated sprints.

Other studies have shown that forwards often receive the ball while sprinting or turning and cover almost 64% of their high intensity running distance with ball possession. In addition, players involvement with the ball (dribbling, short passes, successful passes) is lower in the second compared with the first half. These tactical aspects are also lower after periods of very high-intensity bouts during the match. These observations raise two points: 1) that players should perform a number of high-intensity drills while in contact with the ball, and 2) to be effective, training should provide scenarios as close to the real match situations as possible.

Tuesday, May 10, 2011

SMALL-SIDED GAMES: HOW MUCH IS ENOUGH FOR FITNESS IMPROVEMENT?

Small-sided games are currently used by many teams as a method for football skill and football-specific fitness improvement. There are several  benefits with this kind of training such as improvement of football skills, training with scenarios as close to the match as possible, more pleasant for the players training method etc. The disadvantages are: inadequate control of training stimulus at the individual basis, non-realistic distances between players and lines etc. To minimize the negative points, coaches can change the space, the number of players and the rules.

Is small-sided games training as beneficial as regular running training for the improvement of fitness at the elite level? There are 5-10 studies in the literature in this issue and their results suggest that small-sided games can be as effective as running training in improving football-specific training in elite players. A summary of these studies is presented below.


Table 1. Summary of studies on the effect of small-sided games on football performance.

Study
Training
Intensity
Period
Performance change

In elite players
4min small-sided games, 2 times/week
High
4 weeks pre-season+8 weeks In season
4% improvement in total distance covered during a match

25% improvement in high-intensity activity during a match

In elite players
6-13 min small-sided games, 2 times/week
High
Preseason
17% improvement in Yo-Yo test

no change in repeated sprints

Monday, May 9, 2011

Vitamin D status: Is it a problem in football players?

While it is well established that vitamin D is necessary for optimal bone health recent evidence suggests that vitamin D status may also affect sports performance. Indeed, vitamin D deficiency may increase the risk of autoimmune diseases and can also have a negative effect on human immunity, inflammation, and muscle function (in the elderly). Thus, it is likely that compromised vitamin D status can affect an athlete's overall health and ability to train (i.e., by affecting bone health, innate immunity, and exercise-related immunity and inflammation).

Although, more studies are needed, it seems that athletes’ vitamin D status is dependent on various factors, such as: total time of training outdoors daily, skin color and geographic location.  Regarding location, new data show that serum 25-hydroxyvitamin D  levels (a marker of vitamin D status) is low in middle east athletes and this could be due to low sun exposure during the hot months of years. It seems also that players in North Europe are at a higher risk of low vitamin D levels in the winter that other players.

Sports scientists should regularly assess vitamin D levels in athletes. Some recommendations to maintain normal vitamin D levels are:
  • Regular sun exposure (5-30min, 2 times/week depending on location, skin color and individual characteristics), or
  • Dietary supplementation with 1,000-2,000 IU vitamin D per day

ERYTHROPOIETIN LEVELS AFTER A SHORT PERIOD OF OXYGEN BREATHING

Erythropoietin (EPO) is a hormone produced by the kidneys when a low oxygen pressure is detected in the blood. EPO release in the blood circulation triggers new red blood cells production and this results in hemoglobin (Hb) levels elevation. An elevation in Hb concentration in the blood will increase oxygen carrying capacity. Studies in athletes have shown that increased Hb concentration is associated with improved endurance.

The search for new methods to increase EPO concentration, that do not violate the rules of WADA, has been of interest to scientists. Five years ago, a research group from Belgium showed that breathing 100% normobaric oxygen for 2 h resulted in 60% increase  in EPO after 36 h (Ballestra et al., 2006). Although no data in performance were published in this study, we can assume that this elevation in EPO would have produced a substantial improvement in performance. Few days ago, another group of researcher from Slovenia and Sweden reported totally different results in aerobically fit males (Keramidas et al., 2011). The results suggested that a short period of normobaric oxygen breathing does not increase EPO concentration.

Whatever the reasons for this debate, the area remains of high interest with, potentially, practical applications in the future.

Thursday, May 5, 2011

COMPARING TEAM PERFORMANCE OF THE ENGLISH PREMIER LEAGUE, SERIE A AND LA LIGA

 

I would like to draw your attention to a recent paper published by Professor Joel Oberstone (Journal of Quantitative Research in Sports, 2011). The aim of his study was to examine the differences between the three leagues using statistical analysis. To do so, 18 game measures clustered in 5 groups (defending, goals attempted, passing, crossing and discipline) were analysed.

The main findings were
1) Serie A has a more attacking game than the English Premier League (EPL). They also score more and are the statistically significant best passing league of the three.
2) The EPL is the toughest marking (higher number of tackles) among the 3 leagues. It is interesting though that EPL has fewer fouls, yellow and red cards.
3) La Liga score more goals per game that the other 2 leagues. They also have the highest % of shots on target and also the highest rate of shots resulting in goals. It is the most attacking league.

5 TIPS TO FOOTBALL TALENTS DEVELOPMENT

1. ATTRACT THE BEST. You must create an environment that attracts the best players in your region.
2. SEPARATE THE BEST PERFORMERS FROM THE REST. It is important to evaluate physical, technical and mental characteristics and focus on specific parameters in each individual. Evaluate football-specific decision-making.
3. PRACTISE IS NOTHING! DELIBERATE PRACTISE IS EVERYTHING! Many players work hard but they do not become elite performers. Decide on WHAT EXACTLY needs to be practiced and HOW.
4. RE-EVALUATE. Regularly evaluate performance and thus training methods. Change the means if needed.
5. PLAN EFFECTIVE TRAINING. Please remember: Elite players are superior not because they are different but, probably, because they train MORE EFFECTIVELY.

Wednesday, May 4, 2011

TRAINING IN THE MORNING OR IN THE AFTERNOON?

What we know?
  • Anaerobic power, anaerobic capacity, trunk flexibility, endurance and motivation are better in the afternoon that in the morning.
  • These data are not in football players but in cyclists and normal subjects.
  • There is only one study in football players (Reilly et al., 2007, Chronobiology International 24:507-519).
  • Football players were tested on different days at 08:00, 12:00, 16:00 and 20:00 h. Reaction time, flexibility and juggling were better at 16:00.
  • No effect of day was observed in other tests, like dribbling.
  • A number of teams in Europe train between 10:00 and 12:00 h. Most games start between 12:00 and 21:45 h.

What we do not know
  • The effect of time of day on more football skills.
  • The effect of morning training (08:00-10:00 h) on football performance while playing game in the afternoon (after 16:00).

Conclusion
  • In football players, it seems that performance at certain physical and skill tests is better in the afternoon than in the morning.
  • Data on football players are very limited.
  • In other sports, accuracy of action has been shown to be better in the morning than in the afternoon (Edwards et al. 2005. Ergonomics 48: 1488-1498) and this should also be taken into consideration in training planning.